1. Field of the Invention
The present invention relates generally to medical apparatus and methods. More particularly, the present invention relates to apparatus and methods for sealing a blood vessel penetration disposed at the end of a tissue tract.
A number of procedures in diagnostic and interventional cardiology rely on the introduction of a catheter into a blood vessel through a penetration in a blood vessel wall disposed at the end of a tissue tract, typically accessing a femoral artery in a patient's groin. The penetration is usually created by the Seldinger technique where a needle penetration is first formed, and the penetration subsequently dilated prior to placement of an access sheath. Diagnostic and/or interventional catheters may then be advanced to the coronary arteries using a guidewire which has been introduced over the aortic arch. At the end of the procedure, the guidewires, catheters, and access sheath are removed, leaving the blood vessel penetration and tissue tract opened and in need of closure.
The most common technique for closing the vascular wall penetration is to apply pressure on the skin over the tissue tract. After a time, clotting will occur and the healing process will initiate. Reliance on the patient's own clotting mechanism, however, is complicated since most patients have been treated with heparin or other blood thinning agents to reduce the risk of clotting and embolization during the procedure itself.
A number of improvements over pressure-induced clotting have been proposed. For example, the introduction of gelatin or other bio compatible plug materials or glues have been proposed by a number of inventors, and commercial systems are available under the Vasoseal® and Angioseal® trade names. As an alternative to sealing using such plug materials, suturing the vascular penetrations has been proposed and commercialized under the Prostar® XL and The Closers™ trade names.
Of particular interest to the present invention, the application of energy at or near the site of the vascular penetration to cauterize the penetration has been proposed by several inventors. For example, U.S. Pat. No. 4,929,246, describes methods and systems for applying laser energy to thermally seal a vascular penetration site. The method and system described, however, are both costly and complex. U.S. Pat. No. 5,415,657 describes a probe which may be placed through a tissue tract and positioned by pressing against the outside wall of the blood vessel. A penetration in the wall is then cauterized by applying energy directly to the vessel wall. This method is difficult and unreliable since it is difficult to properly position the cautery surface of the device and requires a great deal of operator training. There is great risk that the cautery surface will pass outward from the tissue tract into the lumen of the blood vessel, in which case the penetration would not be sealed and there is a risk of damage to the blood vessel wall. Even when properly placed, direct heating of the vessel wall can be ineffective and risk damage to the blood vessel wall. A third approach is described in U.S. Pat. No. 5,507,744. The vascular penetration is closed and sealed using heat generated in or thermally conducted to the tissue to induce tissue fusion. Usually, forceps incorporated within the device collapse the tissue against an electrode which delivers radio frequency energy directly into the tissue. The apparatus is complicated and requires careful manipulation to properly grasp the wall and position the electrode. In at least some instances, it is necessary to remove a guidewire from the newly sealed tissue at the end of the procedure, thus risking breach of the newly formed seal. Finally, the method and device introduce significant heat into the vessel wall, risking untended injury.
For these reasons, it would desirable to provide additional and improved methods and apparatus for closing vascular penetrations at the end of tissue tracts formed for vascular access. Such methods and apparatus should be easy to use, create reliable tissue tract closure, minimize or eliminate the risk of injury or damage to the blood vessel wall or other portions of the tissue, in general overcome the deficiencies of the prior art noted above. At least some of these objectives will be met by the invention described hereinbelow.
2. Description of the Background Art
Devices for applying energy to close blood vessels and vascular penetration are described in U.S. Pat. Nos. 4,929,246; 5,415,657; 5,507,744; and 6,077,261. Devices for closing vascular penetrations by deploying a closure assembly and delivering a sealant behind the closure assembly are described in U.S. Pat. Nos. 5,782,860; 5,922,009; 5,951,589; 6,045,570-; and 6,056,769.